A conventional navigation apparatus receives congestion information from a road traffic management center to thereby display the received congestion information on a road map in a display unit. Thus, a user is notified of the congestion on a road (see Patent document 1).
Another apparatus displays a legal speed limit on a road on which a subject vehicle travels to thereby inform a driver of the speed limit (see Patent document 2).
Each of the congestion information and the speed limit is displayed on each display unit; therefore, both cannot be displayed at the same time on a single screen window in a display unit. For instance, multiple roads may be selectable as a route. A first road has a high speed limit and is congested, while a second road has a low speed limit and is not congested. In this case, a user needs a time in determining which road, the first or the second, should be selected.                Patent document 1: JP-2002-71365 A        Patent document 2: JP-H5-67294 A        